Fixes from orbitalturtle review

To be squashed into dcee480

teos/src/carrier.rs

@@ -148,11 +148,15 @@ impl Carrier {
     }
 
     /// Checks whether a given transaction can be found in the mempool.
+    ///
+    /// This uses `getrawtransaction` under the hood and, therefore, its behavior depends on whether `txindex` is enabled in bitcoind.
+    /// If `txindex` is disabled (default), it will only pull data from the mempool. Otherwise, it will also pull data from the transaction
+    /// index. Hence, we need to check whether the returned struct has any of the block related datum set (such as `blockhash`).
     pub(crate) fn in_mempool(&self, txid: &Txid) -> bool {
         self.hang_until_bitcoind_reachable();
 
         match self.bitcoin_cli.get_raw_transaction_info(txid, None) {
-            Ok(_) => true,
+            Ok(tx) => tx.blockhash.is_none(),
             Err(JsonRpcError(RpcError(rpcerr))) => match rpcerr.code {
                 rpc_errors::RPC_INVALID_ADDRESS_OR_KEY => {
                     log::info!("Transaction not found in mempool: {}", txid);

teos/src/responder.rs

@@ -592,7 +592,10 @@ impl chain::Listen for Responder {
     fn block_disconnected(&self, header: &BlockHeader, height: u32) {
         log::warn!("Block disconnected: {}", header.block_hash());
         self.carrier.lock().unwrap().update_height(height);
-        self.tx_index.lock().unwrap().fix(header);
+        self.tx_index
+            .lock()
+            .unwrap()
+            .remove_disconnected_block(header);
 
         for tracker in self.trackers.lock().unwrap().values_mut() {
             // The transaction has been unconfirmed. Flag it as reorged out so we can rebroadcast it.